µMicrophone

This microphone is easy to make and sounds good for close-up miking.
It is especially nice for miking stringed instruments. The primary
component for this microphone is a Panasonic
condenser microphone cartridge.

Figure 1 shows the basic circuit for use with the microphone
cartridge. C1 = 1 µF.
Using a 1 µF capacitor sounds the most natural; however,
for more bass sound a
100 µF or 1000 µF is good. R1 = 2.2 kOhm.

Figure 1: Basic microphone circuit

Other considerations

you might want to coat the back of the cartridge when it is
finished with some sort of sealant to prevent any grounding
noise when holding it.

black colored wire might be nice to minimize the presence of the
wires, but make sure you know which wire is which if both
wires are the same because the wires cannot be switched.

Alternate circuits

Figure 2 shows some additions to the circuit diagram shown
in figure 1. The components C2=1000 µF and
R2=R1/10=220 Ohms are used to prevent clicks
when attaching or detaching the battery from the circuit.
C2=100µF is also good but allows more click sound.
C2 less than 1µF doesn't prevent much clicking
at all. Adding C2 and R2 will slightly lower
the amplitude detection of high frequencies, but not greatly.

R3=100kOhm can be used to discharge the C1
capacitor to prevent clicks when plugging in the microphone.
This resistor causes a somewhat noticeable decrease in higher
frequencies.